@article {2031,
	title = {Emerging model systems in evo-devo: horned beetles and the origins of diversity},
	journal = {Evolution and Development},
	volume = {9},
	number = {4},
	year = {2007},
	month = {jul/aug},
	pages = {323-328},
	abstract = {Horned beetles and beetle horns are emerging as a model system suited to address fundamental questions in evolutionary developmental biology. Here we briefly review the biology of horned beetles and highlight the unusual opportunities they provide for evo-devo research. We then summarize recent advances in the development of new approaches and techniques that are now available to scientists interested in working with these organisms. We end by discussing ways to implement and combine these new approaches to explore new frontiers in evo-devo research previously unavailable to reseachers working outside traditional model organisms. },
	author = {Moczek, Armin P. and Andrews, Justin and Kijimoto, Teiya and Yerushalmi, Yoram and Rose, Debra J.}
}
@article {2036,
	title = {Rapid evolution of a polyphenic threshold},
	journal = {Evolution and Development},
	volume = {5},
	number = {3},
	year = {2003},
	pages = {259-268},
	abstract = {Polyphenisms are thought to play an important role in the evolution of phenotypic diversity and the origin of morphological and behavioral novelties. However, the extent to which polyphenic developmental mechanisms evolve in natural populations is unknown. Here we contrast patterns of male phenotype expression in native and exotic and ances- tral and descendant populations of the horn polyphenic bee- tle, Onthophagus taurus .  Males in this species express two alternative morphologies in response to larval feeding condi- tions. Favorable conditions cause males to grow larger than a threshold body size and to develop a pair of horns on their heads. Males that encounter relatively poor conditions do not reach this threshold size and remain hornless. We show that exotic and native populations of O. taurus  differ significantly in the body size threshold that separates alternative male phenotypes. Comparison with archival museum collections and additional samples obtained from the native range of O. taurus  suggests that allometric differences between exotic and native populations do not reflect preexisting variation in the native range of this species. Instead, our data sug- gest that threshold divergences between exotic and native populations have evolved in less than 40 years since the introduction to a new habitat and have proceeded in oppo- site directions in two exotic ranges of this species. Finally, we show that the kind and magnitude of threshold diver- gence between native and exotic populations are similar to differences normally observed between species. Our re- sults support the view that certain components of the de- velopmental control mechanism that underlie polyphenic development can evolve rapidly in natural populations and may provide important avenues for phenotypic differentia- tion and diversification in nature. We discuss the role of developmental control mechanisms in the origin of allo- metric diversification and explore potential evolutionary mechanisms that could drive scaling relationship evolution in nature.},
	author = {Moczek, Armin P. and Nijhout, H. Frederik}
}
@article {2109,
	title = {Rapid shape divergences between natural and introduced populations of a horned beetle partly mirror divergences between species},
	journal = {Evolution and Development},
	volume = {10},
	number = {2},
	year = {2008},
	pages = {166-175},
	abstract = {Onthophagus taurus is a polyphenic beetle in which males express alternative major (horned) and minor (hornless) morphologies largely dependent on larval nutrition. O. taurus was originally limited to a Turanic--European-- Mediterranean distribution, but became introduced to several exotic regions in the late 1960s. Using geometric morphometrics, we investigate the present-day morphological shape differentiation patterns among native (Italian) and introduced (Western Australian and Eastern US) popu- lations. We then contrast these divergences to those observed between native O. taurus and its sympatric sister species O. illyricus. Our analysis failed to find significant divergences between O. taurus populations in external morphological traits (head, pronotum) when analyses were conducted separately for each sex. However, when sexes and male morphs were analyzed together, three important differences among populations emerged. First, relative warp analyses showed that native and introduced populations diverged in certain shape components that normally distin- guish major and minor male morphs. Second, comparison of covariation of body regions (head vs. pronotum) in the three populations showed that populations diverged in the nature of this covariation, suggesting that different body regions are not totally constrained to evolve in concert. Lastly, and most importantly, the analysis of genitalic shape revealed little to no divergence of female genitalia, but unexpected substantial differentiation of male genitalia among the three O. taurus populations. This suggests that genitalic shape divergence can occur extremely rapidly even in the absence of sympatry and possible reinforcement, and that the genitalia of males and females may diverge independent of one another, at least during the early stage of interpopulational divergence. Interpopulation divergences in O. taurus mirrored aspects of interspecific divergences between O. taurus and O. illyricus in some cases but not others. },
	author = {Pizzo, A. and Roggero, A. and Palestrini, Claudia and Moczek, Armin P. and Rolando, Antonio}
}
